In general, a fluorescent lamp or an incandescent lamp is widely used as a room lighting, but has demerits of short life time, low luminance and low energy efficiency. Therefore, an LED lighting apparatus employing light emitting diode (LED) with relatively longer life time, higher luminance and lower power consumption as a light source is increasing.
Especially, a bulb type LED lighting apparatus capable of replacing a compact fluorescent lamp (CFL), which can be combined with a bulb socket without any additional device to be used, is actively developed.
Conventionally, the LED lighting apparatus for replacing the CFL is similar to an LED lighting apparatus for replacing incandescent lamp in design, so that the degree of design completion is not high. That is, the design that a circuit board on which LEDs are arranged is installed at a heat sink with a hemispherical shape, and a diffusion cover with a dome shape is attached, is dominating.
However, a large portion of the conventional heat sink includes an outer heat dissipating fins protruding outward to improve heat dissipation efficiency to deteriorate appearance.
On the other hand, the LED lighting apparatus includes an LED driver for driving light emitting diodes by converting alternating power provided externally into direct power that is proper to the light emitting diodes, and the shape and position of the LED driver determine the design of the product. Therefore, there exists a try changing the LED driver for improving outer design and heat dissipation efficiency.
In designing the LED driver, the LED driver requires an electrolytic capacitor. The electrolytic capacitor is sensitive to temperature, and the lifetime decreases when the temperature becomes higher. The light generating module generates most portions of heats, so that the temperature of the electrolytic capacitor becomes higher and the lifetime of the electrolytic capacitor decreases when the electrolytic capacitor is disposed near the light generating module.
Further, the parts generating heats are overlapped to further raise the temperature. That is, the light generating module generating a large portion of heats are adjacent to the electrolytic capacitor of the LED driver to raise temperature of the electrolytic capacitor, and raising temperature of the light generating module and the LED driver overlaps to further raise the temperature.